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Search Results: 1 - 10 of 18774 matches for " Felipe Torres "
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Rasgos perennes de la crisis alimentaria en México
Torres Torres, Felipe;
Estudios sociales (Hermosillo, Son.) , 2010,
Abstract: the food crisis that took place in mexico in 2008, which was reflected in the increase of international prices of staples, was not a new phenomenon. it was directly related to the accentuation of a structural problem represented by an insufficiency in agricultural supply at domestic level. this shortage presents asymmetries in access to food products, and has strong repercussions in people's nutritional situation. the truth is that it was the first large crisis in the context of free market that intensified itself as an effect of the global economic recession, in addition to the accumulated deterioration in the purchasing capacity of nearly half of the mexican population.
Rasgos perennes de la crisis alimentaria en México
Felipe Torres Torres
Estudios sociales (Hermosillo, Son.) , 2010,
Abstract: La crisis alimentaria registrada en México durante el a o 2008, la cual se manifiesta con el alza de los precios internacionales en productos básicos, no es nueva. En todo caso corresponde a la agudización de un problema estructural que parte una insuficiente oferta agrícola interna, que presenta asime-trías en la accesibilidad y repercute severamente en los problemas nutricionales de la población. Se trata, eso sí, de la primera gran crisis de la fase de libre mercado que se recrudece con la recesión económica mundial, a lo cual se suma el deterioro acumulado del poder adquisitivo de cerca de la mitad de la población mexicana que impacta en su capacidad de compra y afecta las condiciones nutricionales.
Random modification effect in the size of the fluctuation of the LCS of two sequences of i.i.d. blocks
Heinrich Matzinger,Felipe Torres
Mathematics , 2010,
Abstract: The problem of the order of the fluctuation of the Longest Common Subsequence (LCS) of two independent sequences has been open for decades. There exist contradicting conjectures on the topic, due to Chvatal - Sankoff in 1975 and Waterman in 1994. In the present article, we consider a special model of i.i.d. sequences made out of blocks. A block is a contiguous substring consisting only of one type of symbol. Our model allows only three possible block lengths, each been equiprobable picked up. In this context, we introduce a random operation (random modification) on the blocks of one of the sequences. In the present article, we develop the techniques to prove the following: if we suppose that the random modification increases the length of the LCS with high probability, then the order of the fluctuation of the LCS is as conjectured by Waterman. This result is a key technical part in the study of the size of the fluctuation of the LCS for sequences of i.i.d. blocks, developed by Matzinger and Torres.
Fluctuations of the Longest Common Subsequence for Sequences of Independent Blocks
Heinrich Matzinger,Felipe Torres
Mathematics , 2010,
Abstract: The problem of the fluctuation of the Longest Common Subsequence (LCS) of two i.i.d. sequences of length $n>0$ has been open for decades. There exist contradicting conjectures on the topic. Chvatal and Sankoff conjectured in 1975 that asymptotically the order should be $n^{2/3}$, while Waterman conjectured in 1994 that asymptotically the order should be $n$. A contiguous substring consisting only of one type of symbol is called a block. In the present work, we determine the order of the fluctuation of the LCS for a special model of sequences consisting of i.i.d. blocks whose lengths are uniformly distributed on the set $\{l-1,l,l+1\}$, with $l$ a given positive integer. We showed that the fluctuation in this model is asymptotically of order $n$, which confirm Waterman's conjecture. For achieving this goal, we developed a new method which allows us to reformulate the problem of the order of the variance as a (relatively) low dimensional optimization problem.
Hacia una política territorial del desarrollo rural de México
Torres Torres, Felipe;Delgadillo Macías, Javier;
Convergencia , 2009,
Abstract: there is a persistent concern in mexico on guiding the role that the countryside should play in the future of national development, considering its present difficulties in backwardness and stagnation. a vision of how to move this process is present in the new law on sustainable rural development (ley de desarrollo rural sustentable), which suggests an approach to development from the territory as a subject of action and new processes are recognized as rural routes to rebuild the fabric of rural life. however, there is still the need to express this law in an operational policy that actually includes realizable alternatives to reverse the depopulation of the countryside caused by marginalization and massive migration in the face of the need for peasant's survival. in this case, the proposal should lead to its greater possible scope the territorial approach to rural development and operational strategy. therefore, what we are proposing in this paper is to raise some points that may be strategic in defining a rural policy for the country, from territorial approach and regional development, taking into account the dimensions of economic and social fragmentation which generate the abandonment of the countryside, but also as a new scale of opportunities that entails the presence of rural activities increasingly diverse and complex which could be translated into the new rural development policy that we endeavor for as a way to reduce social imbalances in the country.
Hacia una política territorial del desarrollo rural de México
Felipe Torres Torres,Javier Delgadillo Macías
Convergencia , 2009,
Abstract: Existe en México una preocupación permanente por reencauzar el papel que deberá jugar el campo en el futuro del desarrollo nacional, considerando sus dificultades actuales de atraso y estancamiento. Una visión de cómo impulsar este proceso está presente en la nueva Ley de Desarrollo Rural Sustentable, de la cual se desprende un enfoque del desarrollo a partir del territorio como sujeto de acción, y se reconocen los nuevos procesos rurales como ejes para reconstituir el tejido de la vida rural. Sin em bargo, todavía falta expresar esta ley en una política operativa que incluya efectivamente la concreción de alternativas para revertir el despoblamiento del campo, provocada por la marginación y emigraciones masivas ante la necesidad de sobrevivencia campesina En tal caso, la propuesta debería llevar hasta sus mayores alcances posibles el enfoque territorial del desarrollo rural como estrategia operativa. Por lo tanto, lo que nos proponemos en este trabajo es plantear algunos aspectos que pueden ser estratégicos en la definición de una política rural para el país, a partir del enfoque territorial y regional del desarrollo, teniendo en cuenta las dimensiones de fragmentación económica y social que genera el abandono del campo; pero también como nueva escala de oportunidades que trae consigo la presencia de actividades rurales cada vez más diversas y complejas, las cuales puedan traducirse en la nueva política de desarrollo rural que tanto anhelamos como forma de abatir los desequilibrios sociales en el país.
On hitting times for simple random walk on dense Erd?s-Rényi random graphs
Matthias L?we,Felipe Torres
Mathematics , 2013,
Abstract: Let $G(N,p)=(V,E)$ be an Erd\"os-R\'enyi random graph and $(X_n)_{n \in \mathbb{N}}$ be a simple random walk on it. We study the the order of magnitude of $\sum_{i \in V} \pi_ih_{ij} $ where $\pi_i=d_i / 2|E|$ for $d_i$ the number of neighbors of node $i$ and $h_{ij}$ the hitting time for $(X_n)_{n \in \mathbb{N}}$ between nodes $i$ and $j$, in a regime of $p=p(N)$ such that $G(N,p)$ is almost surely connected as $N\to\infty$. Our main result is that $\sum_{i \in V} \pi_ih_{ij} $ is almost surely of order $N(1+o(1))$ as $N\to \infty$, which coincides with previous results in the physics literature \cite{sood}, though our techniques are based on large deviations bounds on the number of neighbors of a typical node and the number of edges in $G(N,p)$ together with recent work on bounds on the spectrum of the (random) adjacency matrix of $G(N,p)$.
Músculo Elevador de la Escápula: Caracterización Macroscópica
Mardones Valdivieso,Felipe; Rodríguez Torres,Alberto;
International Journal of Morphology , 2006, DOI: 10.4067/S0717-95022006000300021
Abstract: recent surgical techniques and applications have prompted a thorough anatomical study of the levator scapulae muscle. however, there are still questions regarding its morphology which are important to consider if it is to be used as a reconstructive tool. in this study, 11 human corpses were used (8 males and 3 females), with an average age of 70 years. we dissected in a step-wise manner both sides of 9 cervical and scapular regions, and in 2 cases, only one side. different macroscopic features were analyzed such as: configuration, location, muscle origins and insertions, direct relationships and variations. the muscle was located in the posterior and lateral cervical as well as scapular regions. it resembles a cinch, as it originates from various muscular fascicles and inserts as a common muscular mass. we observed an average of 3.95 (s.d ±0.85) fascicles per muscle, with total lengths in the range between 14.9 c.m. to 18.3 c.m. the fascicles originated from tendons from the cervical vertebrae, with an average of 3.9 (s.d ±0.78) per muscle. distally, the muscle inserted in various points of the scapulae, as well as the fasciae of the serratus anterior muscle. just before its insertion, we also observed the splitting of the muscle into 2 flaps. several vascular, nervous, muscular and lymphatic elements in the cervical and scapular regions were closely related to the levator scapulae muscle. also, anatomical variations were observed regarding the muscle′s origins, muscle fibers and insertions. the developmental events of the muscle are useful to understand some of the macroscopic observations. although some of its morphologic features discourage its use (close relationships, variations), others (length of fascicles and location) enlight it as a good alternative in the reconstructive surgery of the head and neck
Músculo Elevador de la Escápula: Irrigación e Inervación
Mardones Valdivieso,Felipe; Rodríguez Torres,Alberto;
International Journal of Morphology , 2006, DOI: 10.4067/S0717-95022006000400012
Abstract: the use of muscular flaps as a reconstructive tool requires a thorough anatomical knowledge of its blood supply and innervation. although surgical applications of the levator scapulae muscle have contributed to this matter, there are still questions regarding these morphologic features. in this study, 11 human corpses were used (8 males and 3 females), with an average age of 70 years. in 7 of these, an arterial repletion was performed prior to dissection. the latter was done in a step-wise manner in both sides of 9 cervical and scapular regions and in 2 cases, only one side. several aspects of the arterial blood supply and innervation of the muscle were analyzed. we identified 4 possible sources for arterial irrigation: vertebral (v), ascending (ac) and transverse cervical (tc) and dorsal scapular (de). overall, the blood supply occurred as a combination of the above, with tc and de providing the dominant pedicles in most cases. differences were noted in the effective muscular irrigation between the arteries, wich was 100% for v, 80% for ac, 85% for tc and 55% for de. regarding the location of the vascular pedicles, v irrigated the muscle origins, ac irrigated the upper segment, whereas tc and de irrigated the middle and lower muscle segments. based on the mathes and nahai classification, the majority had a type v irrigation pattern. in most cases, the innervation came from the third and fourth spinal cervical nerve (c3 and c4), although the fifth spinal cervical nerve (c5) also participated through the dorsal scapular nerve. the motor points for c3 and c4 were located in the upper segment of the muscle, whereas for c5 it was located in the lower segment. due to its generous and heterogeneous arterial supply and segmentary innervation, the muscle is a good alternative to consider if it is to be used as a reconstructive flap
Seasonal variation in natural populations of Drosophila spp. (Diptera) in two woodlands in the State of S?o Paulo, Brazil
Torres, Felipe Rafael;Madi-Ravazzi, Lilian;
Iheringia. Série Zoologia , 2006, DOI: 10.1590/S0073-47212006000400008
Abstract: the composition and the seasonality of the natural populations of drosophila species in relation to the climatic variables temperature and rainfall were analyzed from september 1998 through october 1999 by monthly collections, in two woodlands in the northwest of the state of s?o paulo, brazil. the diversity dominance component curves were inclined, reflecting low diversity and high dominance of few species. among the 25 species recorded, drosophila sturtevanti duda, 1927 was the most frequent and abundant. on the opposite to data in literature, d. paranaensis barros, 1950 abundance and frequency were greater than those from d. mercatorum patterson & wheeler, 1942. a positive correlation between abundance and rainfall was observed for d. nebulosa sturtevant, 1916. these data are indicative of changes in the populations structure due to new adaptive strategies arised in response to environmental modifications.
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